Vehicle to vehicle (V2V) communications is a communications technology used to perform data transmission and information exchange between vehicles by using a wireless communications technology. As important content in a research of an intelligent transportation system (ITS) and the Internet of Vehicles, the V2V communications mainly provides and supports applications and service transmission that are related to road transportation safety, and is widely recognized as a key technology for improving vehicle driving safety and reducing traffic accidents.
A V2V service carried in the V2V communications is implemented by transmitting a V2V message. The V2V message mainly includes some information related to a vehicle driving status, for example, at least one of a vehicle speed, a driving direction, a longitude and a latitude, an acceleration, whether a brake is applied, whether a lane changes, or the like; and/or some information related to a surrounding road environment, for example, at least one of an accident, a road construction, a transportation facility fault, and the like. By using the V2V communications, a vehicle may exchange V2V messages with another vehicle near the vehicle, so that a vehicle driving system can obtain road condition information or receive an information service related to vehicle driving safety in a timely manner, and a vehicle driver or the vehicle driving system is assisted in predetermining a danger and performing a corresponding operation, to avoid an accident as far as possible. The V2V communications is related to key information of vehicle driving safety, and V2V messages need to be exchanged between vehicles in a timely and accurate manner. Therefore, the V2V communications has communications requirements of “high reliability and a short latency”.
Standardization work performed by the 3rd Generation Partnership Project (3GPP) on “Long Term Evolution (LTE)-based vehicle to everything (V2X) communications” covers vehicle communications scenarios such as V2V, vehicle to infrastructure (V2I), and vehicle to pedestrian (V2P). The standardization work aims to provide, based on an LTE communications system, wireless vehicle communications related to road safety. LTE-based V2V communications is an important component of the standardization work, and provides two communications technologies: device to device (D2D) direct communications and LTE base station-based transit communications.
The D2D direct communications technology allows user equipments (UE) to directly communicate with each other by using a PC5 interface. A transmission latency of the technology is relatively low. However, because configured resources are very limited, V2V message transmission congestion and a data collision may easily occur.
In the LTE base station-based transit communications technology, communication is performed by using a Uu interface, and reliability is relatively high. However, UE first needs to send data to a base station, and then the base station forwards the data to another UE. A transmission latency is relatively high, and a relatively large quantity of resources are occupied.
It can be learned that user equipment may not meet a communications requirement of a V2X service regardless of whether the user equipment performs V2X communication by using a PC5 interface or a Uu interface.